Stitch length adjusting mechanism



p 1946- c. w. JO'HNSON STITCH LENGTH ADJUSTING MECHANISM Original FiledAug. 12, 1939 2 Sheeis-Sheet 1 CARL VV. JOHNSON ATTORNEY.

Sept. 24, 19 46. I JOH NSON 2,407,986 I STITCH LENGTH'ADJUSTING MECHWISMOriginal Filed Aug. 12, i939 2 Sheets-Shet 2 FIG. 5

FIG, 3

INVENTOR CARL W. JOHNSON ATTORNEY Patented Sept. 24, 1946 STITCH LENGTHADJUSTING MECHANISM Carl W. Johnson, Brooklyn, N. Y., assignor toAmerican Machine and Foundry Company, a corporation of New JerseyOriginal application August 12, 1939, Serial No.

Divided and this application August 11, 1942, Serial No. 454,353

This invention relates to sewing machines, and the present applicationis a divisional application from the earlier application, Serial No.289,907, filed August 12, 1939, for Sewing machine and relates toimprovements in mechanism for controlling the length of stitches to beformed during the operation of the machine.

The invention relates further to sewing machines, especially of theunder and over stitch type, utilizing a double pointed needle having aneye located between the points, and has particular reference tomechanism for controlling the length of stitches formed by the movementof this type of needle and a thread through work being sewed.

In order to meet all of the demands which may be imposed upon my machinein sewing all of the various kinds of materials which may be handledthereon, it may be necessary from time to time or during the sewing ofany particular work or material to change the length of the stitch fromlong to short or vice versa, or to utilize a certain length stitch forone part and another length stitch for another, etc. For that reason myinvention further consists in the provision of improved mechanism whichmakes it possible to change the length of the stitch from time to timewhenever necessary. This mechanism may operate automatically or beadjusted manually to change the length of the stitch whenever. desired.

It is a further object of my invention to provide improved mechanism foruse with a machine employing a double pointed needle in which changes institch length are made automatically during the operation of themachine.

It is also an object of my invention to provide mechanism whichautomatically changes alternate stitch lengths during the operation ofthe machine.

It is also an object of my invention to provide a sewing machine of thetype forming over and under stitches of a predetermined length, andselective means for changing from one length to another either manuallyor automatically.

With these and other objects'not specifically mentioned in view, theinvention consists in certain' combinations and constructions which willbe hereinafter fully described, and then specifically set forth in theclaims hereunto appended.

In the accompanying drawings which form a Part of this specification,and wherein the several reference characters designate the same or likeelements:

4 Claims. (01. 112-210) Figure 1 is a partial front elevation of thesewing machine embodying my improved stitch length controllingmechanism; t

Figure 2 is a detail View taken on line 22 of Figure 1 showing one formof the feeding.

in which it is possible to produce alternate short and long stitchesautomatically;

Figure 5 is an end view of Figure 4;

Figure 6 is a sectional partial side elevation of a detail of the workfeeding mechanism taken on line 5-6 of Figure l; and v Figure 7 is aplan view of a detail of the stitch length adjusting mechanism shown inFigure. 3.

Referring to the drawings, Figure 1 shows a preferred embodiment of myinvention adapted for use in a machine of the type employing a doublepointed needle N having an eye between the points and needle bars 55, 56provided with tapered caps 12 serving to confine spring pressed jaws(not shown), which may be of the type shown in Naftali Reissue PatentNo. 19,653, granted July 23, 1935, which clutch the needle N, to performthe stitching. As shown, the machine comprises a stationary frame I ll,a.sew-.

ing machine head ll extending therefrom and a bracket I 2 supporting thework table 113. Hand wheel 4| is driven in the manner described in my.co-pending application to operate the needle bars and associatedmechanism from a suitablemotor and clutch (not shown) by means of apulley 24, driven by means of a belt 23 running on a pulley 22 carriedby shaft 36 which mounts a pulley I9 over which runs a motor driven beltl8.

It will be understood by those skilled in the art, that in this type ofmachine, needle N is projected back and forth through the work and is,therefore, alternately grasped by the jaws of upper bar. The upperneedle bar upon receiving t e needle from the lower needle bar 56, risesand elevates head 13 from engagement with lug 63. At the moment thisoccurs, the spring pressed jaws clutch the needle by reason of thespring action in needle bar 55, and movement of the jaws into cap 12.The operation of the lower needle bar 56 is effected in the. samegeneral. manner, and hence it will be understood that whenever a head 13is not in engagement with a lug 63, the spring action in each needle barwill. force the gripping jaws into cap I2 and cause the jaws to grip theneedle. The spring action of the jaws acts alternately so that-first oneand then the other bar grips the needle. I

The work is fed over table I3 beneath a presser foot I provided toengage and retain it in sewing position. This foot is secured to aholder 76 clamped to the lower end of aspring' tensioned rod 1'! whichis guided in the lugs 63 and 64 of member 65. The rod 11 is providedwith a. block I8 fitting in the space between the rear wall of member 65and. a. strap 79 secured to a portion of member I55 and in this mannertends to re.- tain the presser foot in alignment with the needle bars.The upper end of the rod TI is provided with a collar till-normallyabutting a. forked block 81- fastened to one end of a pivot shaft, 82.One end of shaft '82 is mounted on a projecting. lug 83 of member 63'and has its other end mounted in a lug. (not shown) secured. to th wall21 of head I.I... At a point along. the length of shaft 82' is mountedan actuator arm 8'6 carrying a stud supporting a head 87 which holds oneend of. arod 88 connected to a link (not shown-)1 in turn. connected to'a manually operated shift plate (not shown) all. as shown and describedin my co-pending application,v Serial No. 289,907 in order to raise andlower foot I5. -By lifting the presser foot the operator may readilyinspect the work or locate new work in sewing position.

When the lower needle bar 55 ascends, causing the. needle N. to push.the thread, through the- Work, thefsudden thfrust or piercing tends toovercome the spring pressure of rod 11 and lift the presser foot '15from the work. It is desirable to have the spring 95 of rod I1. weakenough to allow the presser foot. to. yield upwardly in. order to allowthe work. to be readily manipulated, and to prevent undue pressure onthework. In order'to. overcome any. excess upward movement thereof, aspring actuated arm 96 may be provided, which is in close relationshipwith the, upper end of' rod 11 so that the rod in moving upward willstrike th end of the arm 96, and be forced. back, thereby tending tohold the presser foot in proper operative position relative to the work.Arm 96 is mounted on. a pivot stud (not shown) carried by a bar 98suspended from head II and is urged by a spring (not shown) downwardlyto hold an adjusting screw Illl in abutment with a suitable stop (notshown). The screw III! is provided sothat the. gapbetween rod IT and arm96 may be varied to best; suit. conditions and. when. properly set the.screw is locked in position by any suitable, means, such as'aknurlednutI03'.

Referring to Figure 1, the mechanism for pulling the: loop as formedfrom the thread will now be. described briefly since it forms no part ofthis invention. A gear I75 meshing with th gear 4.4; but rotating at agreater speed. is fixed to. a shaft I16; mounted. in suitable bearings IIT of head l.iand of a stationary member or. drum I18, suitablysupported by head II and frame I0; A gear through suitable drivingconnections shown and described in my co-pending applicato be describedhereinafter.

tion, drives the thread puller I86 in order to pull the loose end of thethread through the work. The thread puller I86 is provided with apointed thread engaging end so mounted that it may rotate around theperiphery of the stationary drum member I18. The chief function of the.thread puller is to engage the loop of thread formed on alternatemovements of the needle and pull the thread through the work, anddispose it about the periphery of the drum in such a manner that the.danger of snarling, fouling or breaking the. thread is practicallyeliminated. Thread, puller I is fixed to the outer end of a carrier arm.I81; which is pivotally mounted on a rotating member (not shown). Theouter end of arm I8! is also provided with a curved guide plate,- =93adapted to engage a tape I94 partly circling the drum I18, which tapeacts to maintain the thread in orderly fashion and also preventswhipping of the thread as it is placed around the drum. A brush S may befixed beneath the drum IIBi, as shown in Figure I, in

order to act as. a brake and apply a frictional; force upon the threadas itis. being pulled from.

the drum. This adds additional control in handling the thread andprevents it from whipping. about or tangling in any'manner.

The driven sprocket 4.2 (Figure 1) imparts motion to a chain I05 runningover a sprocket. I06. mounted on a shaft I01 supported in a hub ofbracket I08 secured toframe I6.. The opposite end of shaft I0! supportsa coupling I09 (Figure- 2) terminating ina cam surface III] whichimparts up and down motion. to the material feed.

Member I 09 supports a short eccentric. stud, I'I'I' equipped with aroller H2 engaging an elongated slot H3 provided. in the lower. end oflever I I4 fulcrumed on arm H5 which is mounted .on the end of a, pivot.stud H6 secured to frame ['0 by a bolt I'I'I, Lever H4 mounts a stud [I8carrying a follower II9' engaging a slot I20 in th head. of a slottedmember I2 I mounted in a counterbored portion [22. of plug 123turnablysupported' in an. aperture of frame I0.

By loosening the thumb screw I26}. arm [24- maybe moved, and in so.doing shiftr the position.

of slot I20 in member I'ZI, thereby. changing the angular relation of'slot I20 and lever II4., Arm.

I24. is provided with an. arcuate slot. I25 in. order.

to allow said arm to be moved relative to loosened screw I26 in order toadjustthe position of member I20 and secure the slot, IZI' therein inany desired adjusted position relative to fol.- lower' H9.

rection so that the slot therein will be moved.

more towards'th'e horizontal. Sincel'ever H5 is fastened to a fork I 21(Figure. 2) connected t a material feed arm I28", the resulting to. andfro motion imparted to arm I28 can be varied,

thereby making it. possible to adjust. the length. and make longer orshorter stitches as required.

The up and down movement of arm I28 imparted by a cam H0 with whichcoacts a camfollower I29 provided on an arm of lever I30 the leversupportsone end of an adjustablejlinln It will be apparent, therefore,that the more slot H0 is turned towards the vertical,.

I32 which is connected to a depending arm I33 of member I28. The rightend of arm I28 (Figures 1 and 6) is mounted on a pivot stud I40supported in lug I4I of an arm I42 loosely mounted on stud I34. ()ne endof this stud is mounted in a spacing block I43 suitably secured to frameI0.

Material feed plate I35, attached to arm I 28, is provided with acorrugated or toothed work feeding surface adapted to engage and advancethe work. This plate may be of the usual type employed in sewingmachines and is arranged to project upwardly through a slot in plate I3over which the work is fed to and from the needle. IAS each stitch iscompleted, the arm I28 through its connections, is caused to index, thatis, the arm descends slightly below the level of throat plate or tableI3 leaving the work resting thereon and then the arm moves up, engagesand advances the work in readiness for the next stitch, the workremaining in this position while the plate I35 returns to its originalposition.

Referring to the modification shown in Figure 3, the general operationof the feed arm I28 is the same as hereinabove described. Mechanism hasbeen provided, however, to make adjustments in order to control thestitch length for normal stitching, and also make longer or shorterstitches as the case may be according to the requirements with respectto the particular work being sewed. As an example, in sewing the sidesof the fingers of gloves, a normal stitch length is generally used forthe major portions of each glove. However, when the operator proposes tosew the tip portion of the fingers, the normal stitch may be found to betoo long for satisfactory work, and hence means is provided for quicklyshortening the stitch length. At this time, the operator depresses afoot pedal 308 which through connections to be described presently,shifts the position of the slotted stitch contro1 member I2I to produceshorter stitches for sewing the finger tip portion of the glove. Whenthe sewing of the tip portion is completed, the operators foot isreleased from the pedal and normal stitching will be resumed.

An arm 300 (Figure 3) is clamped to member I2I and at its lower endsupports a forked head 30I and a head 302 connected by means of a rod303 to an arm 304 fixed on a pivot shaft 305. An arm 306, also fixed onshaft 305, is actuated by a link 301 connected to a foot pedal 308mounted on a pivot 309. The forked head 30I carries an adjustable link3I0 which at its other end is provided with knurled nuts 3H and 3I2which are turnably and slidably mounted in an aperture 3 I 3 of a holder3I4 secured in a suitable manner to the frame of the machine. Theaperture 3I3 is open at the top and exposes a portion of the shanks 3I5of the nuts 3H and 3I2, the exposed portion of the shanks being engagedby prongs of a flat spring 3I6 which tend to hold said nuts from turningafter the final adjustments have been made.

The knurled nut 3| I provides means for adjusting the position of memberI2I to obtain the length of stitch best suited for different types ofWork. A spring 3I'I having one end attached to arm 304 and its other endsecured to a stationary part of the machine (not shown) normally tendsto hold the shoulder 3I8 of nut 3 in engagement with holder 3I4. Theknurled nut 3I2 governs the length of the short stitch. That is, withthe foot pedal 308 depressed the rod 303 will move arm 300 andconsequently change the position of member I2I by varying the throw oflever arm II 4 which controls the horizontal distance traveled by barI28. The movement of arm 300 causes link 3I0 to remove the shoulder 3| 0of nut 3II from holder SM and advance nut 3I2 until its shoulder 3I9abuts the other end of holder 3 I4 thus halting further movement of arm300. Member I2I retains this position until the foot pedal 300 isreleased, whereupon spring 3II restores the device to its formerposition. It will be apparent that the greater the distance betweenshoulder 3I9 and the end of the holder 3M, the greater will be themovement of arm 300 to set m mber I2I, which consequently results inshorter stitches.

Referring to Figures 4 and 5, another modified stitch control device isshown in which alternate short and long stitches are automaticallyproduced for. decorative work. Accordin to this embodiment, a drivensprocket 320 fixed on a shaft 32I imparts motion to the eccentric IIIand cam IIO to actuate the material feed arm I28 in the same manner asshown in Figures 1, 2 and 3. A gear 322, fixed on shaft 32I, meshes withand drives a gear 323 and its attached gear 324 loosely mounted on studIZIa, while the gear 324 in turn drives a gear 325 and a cam 326 looselymounted on shaft 32I. In this manner, the gearin 322, 323, 324 and 325drives the cam 326 at one-half the speed of cam IIO. Cam 326 engages acam roller 32! carried by a cam lever 328 mountedon shaft I2I. Lever 328is adjustably attached to an arm 329, clamped on shaft I2I by a thumbscrew 330. The lower portion. of arm 329 is pro.- vided with anelongated slot 33I adapted to engage thumb screw 330. By loosening thethumb screw 330, the arm 329 may be moved and in so doing shift theposition of slot I20 of shaft I2I resulting in more or less movement ofarm I 28, as heretofore mentioned.

The cam 326 has a high portion 332 and a low portion 333, the surface332 beingconsiderably longer than 333 and therefore when it engagesfollower 32'! it holds the slotted head of stitch control member I20 ina position to produce a 7 long stitch, as the follower 321 rides ofisurface 332 and approaches surface 333, the slotted head of member I20is turned to a position to produce a short stitch. The continuousrocking of the slotted head results in alternate long and shortstitching of the work.

In the mechanisms hereinabove described it will be evident that I haveprovided means for forming stitches of a predetermined length, andselective mechanism operative either manually or automatically to varythe stitch length by control of the work feeding device in accordancewith the wishes of the machine operator or the demands of a given pieceof work being sewed or decorated.

The invention above described may be varied in construction within thescope of the claims, for the particular device, selected to illustratethe invention, is but one of many possible concrete embodiments of thesame. It is not, therefore, to be restricted to the precise details ofthe structure shown and described.

What is claimed is:

1. In a sewing machine, a work support, means for feeding work to besewed along said support including a work feed bar, and mechanism. forvarying the amount of movement of said means, said mechanism comprisinga lever associated with said bar, a second lever pivoted on saidfirst-named lever, means for oscillating said second lever, a followercarried by said second lever, a slotted member normally engaging saidfollower, anadjusting rod secured to said member, adjusting meansconnected to said rod for setting the length of stitch to be made at apredetermined length, a manually operated device attached to said memberfor shifting said member to change the stitch from one length to anotherat the will of the operator while maintaining the adjustment of saidadjusting means undisturbed, and means for automatically moving saiddevice in the opposite direction to reset said memher in its originaladjusted position.

1 '2. In a sewing machine, the combination with a work support, ofmechanism for feeding work to be sewed along said support, meansassociated with said mechanism for adjusting the length of stitch to bemade, said means including a stitch length control member, means forsetting said member to form stitches of various lengths, an armfixed tosaid member, an adjusting rod, a connection between said arm and one endof said rod, a holder supporting the other end of said rod, adjustingnuts on said holder supported end of said rod, said nuts being locatedon said rod at opposite sides of said holder, means for securing saidnuts in adjusted position on said rod and relative to said holder, oneof said nuts being adjustably positioned on said rod to control theposition of said member for forming a predetermined normal stitchlength, means normally holdin'g said nut in engagement with said holder,and manually operated means for moving said member'to displace said rodand said one of said nuts from said holder and cause said other ofsaidnuts to engage said holder whereby to modify the movement of saidfeeding mechanism and thereby control the length of stitch formed. l

3. In a sewing machine, a work support, means for feeding work to besewed along said support 8 including a workfeed bar, and mechanism forvarying the amount of movement of said means, said mechanism comprisinga lever associated with said bar, a second lever pivoted on saidfirst-named lever, means for oscillating said second lever, a followercarried by said second lever, a slotted member normally engaging saidfollower, means for shifting the position of said slotted member to varythe extent of movement of said lever and travel of said feeding means,and

a manually adjustable device connected to said member for setting thestitch length within predetermined limits, said device including a rodattached to said member, a block slidably mounting one end of said rodand adjustable nuts mounted on said rod at opposite ends of said block.

4 In a sewing machine, a work support, means for feeding work to besewed along said support including a work feed bar, and mechanism forvarying the amount of movement of said means, said mechanism comprisinga lever associated with said bar, a second lever pivoted on saidfirst-named lever, means for oscillating said second lever, a followercarried by said second lever, a slotted member normally engaging saidfollower, means for shifting the position of said slotted member to varythe extent of movement of said lever and travel of said feeding means, amanuallyadjustable device connected to'said member for setting thestitch length within pre- 7 determined limits, said device including arod attached to said member, a blockslidably mounting one end of saidrod and adjusting screws mounted on said rod at opposite ends of saidblock, a second rod also attached to said member, and manually operatedmeans operative at will for moving said second rod and shift theposition of said member for changing the stitch length within said setlimits.

CARL W. JOHNSON.

